Change the test that assumes that a hashtag with # will remain as-is

This does not seem to be the intended behaviour, as the code that produces it
did not actually ever do anything and just returned the tag as-is.

See
lib/pleroma/web/activity_pub/object_validators/tag_validator.ex
and
https://git.pleroma.social/pleroma/pleroma/-/merge_requests/4358#note_112681

At least Mastodon and Misskey output tags without the # from their API,
so in reality tags with the hash should rarely happen.

test/pleroma/web/activity_pub/transmogrifier/note_handling_test.exs

@@ -200,7 +200,7 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier.NoteHandlingTest do
       assert match?(
                %{
                  "href" => "http://mastodon.example.org/tags/moo",
-                 "name" => "#moo",
+                 "name" => "moo",
                  "type" => "Hashtag"
                },
                Enum.at(object.data["tag"], 1)